Archive Compression $ DeDupe

[John_Huber]

I need a little help on archive compression.  I have read that all data is compressed as it is stored in the archives.   I have also read that .CAB files are not compressed and .DVS files are not compressed.   I am thinking that data moved to CAB files is already compressed and does not need to be compressed further.  I am not sure about the .DVS files.

I would also like to confirm that the only deduplication taking place is Single Instance Storage within the Vault stores.  It is a file level process and not a block level process.

All help will be much appreciated.

[JesusWept3 · Accepted solution]

DVS files are compressed by default except when they become a certain size and they become DVF files
Items going in to CAB files are not compressed, because it slows things down and typically when you compress a file already compress, it makes the CAB file bigger

EV does not do block level deduplication. Instead it hashes the attachments before it turns in to a DVSSP, if the hash is not found within the Fingerprint database, then a new DVSSP file is made, if the hash IS found, then a pointer to the file in the database is made and the same item won't be stored

This is different to how it works if you have a device that does compression and deduplication, then EV will simply let the device handle it

[A_J1]

Just to add: 

Collection (.CAB) is used to SPEED UP your backups of you partitions as backing up small DVS files take more time than backing up CAB files.